Field of the Invention
The present invention relates to a method and an apparatus for developing photosensitive lithographic plate on which an image has been exposed.
A photosensitive lithographic plate on which an image has been exposed is transported to an apparatus for developing the photosensitive lithographic plate in which it is subjected to development.
The development can be realized by a spraying method arranged such that the developer is supplied through a spray to the surface of the photosensitive material, a dipping method arranged such that the photosensitive lithographic plate is introduced into a developing tank in which the developer is contained, and a metering method arranged such that a developer necessary to complete the development is applied to the surface of the photosensitive lithographic plate. However, since the above-described spraying method uses the developer in a recirculated manner, it can gradually deteriorate due to eluted components from the photosensitive layer of the photosensitive material. Furthermore, in a case where an alkaline developer is employed in this spraying method, the developer also deteriorates due to carbon dioxide in air.
The dipping method needs a large quantity of developer to be used since the photosensitive lithographic plate has to be dipped into the developer. Furthermore, as a considerably large number of plates is developed, the developer deteriorates. In order to prevent the above-described deterioration of the developer, various methods of replenishing the developer have been disclosed in Japanese Patent Laid-Open No. 50-144502, Japanese Patent Laid-Open No. 54-62004, Japanese Patent Laid-Open No. 55-115039, and Japanese Patent Laid-Open No. 56-12645. However, these methods need a complicated and expensive apparatus. Furthermore, when used developer is replaced by unused one, developer which can be used may be discarded. Therefore, efficient use of the developer without waste can not be achieved by the dipping method.
On the other hand, quantity of the developer of the metering method can be reduced as compared with that of the above-described spraying method or the dipping method and replenishing device or the circulating device is not necessary, and thus the structure of the apparatus is simplified.
A metering method has been proposed in Japanese Patent Patent Application No. 62-87964. According to this method, a photosensitive lithographic plate is transported substantially vertically while the developer is applied onto the plate.
However, according to this method, the developer applied as described in the above naturally drops, and spoils the photosensitive lithographic plate, the inside of the apparatus or the outside of the apparatus.
Furthermore, the above-described vertical transportation of the photosensitive lithographic plate needs to be provided with guides and conveying rollers for the purpose of turning the direction of the conveyance of the photosensitive lithographic plate from the substantially horizontal direction to the substantially vertical direction. To this end, a method has been disclosed that is arranged such that the photosensitive lithographic plate is conveyed in the horizontal direction with the photosensitive layer thereof faced upward and developer is applied to the layer.
However, when the developer is applied to the photosensitive lithographic plate conveyed in substantially the horizontal direction according to the above-described metering method, the developer can be retained on the surface of the plate without any drops where layer of the plate on which an image is recorded is faced upward. However, the developer naturally drops where the layer faces downward. Accordingly, the layer which faces downward cannot be subjected to the development. That is, the both layers of the photosensitive lithographic plate or the layer facing downward of the same are not always developed.